1. Field of the Invention
The present invention relates, in general, to a method of manufacturing a printed circuit board (PCB) for fine circuit formation, and more particularly, to a method of manufacturing a PCB for fine circuit formation, which can be used to economically realize a highly reliable fine circuit pattern by continuously performing mechanical polishing and chemical etching at low expense, in place of a conventional expensive process, such as CMP (Chemical Mechanical Polishing), with regard to a planarization technique, among circuit forming techniques.
2. Description of the Related Art
With the recent rapid advancement of electronic industries, various techniques have been developed in the field of electronic devices and PCBs. In particular, according to the circuit patterning trend toward decreasing the mounting area and increasing the capacity and functionality, techniques for forming fine circuits have been diversified and have been rapidly advanced.
As a planarization technique, among the circuit forming techniques, a new polishing process, called CMP, in which a mechanical removal process and a chemical removal process are combined in a single process, was conceived by IBM Corp., USA, at the end of the 1980s. CMP is a process which must be conducted when fabricating chips on a sub-micrometer scale. Further, the ILD (Interlayer Dielectric) CMP and the metal CMP should be continuously applied on all surfaces of the layers of the device, and the CMP plays a chief role in uniformly planarizing each layer in order to assure a three-dimensional shape. CMP is a polishing process in which a mechanical process and a chemical process are simultaneously conducted, and influence each other.
The present planarization technique mainly depends on the CMP process. For example, U.S. Pat. No. 5,196,353 discloses a planarization technique using a CMP process.
In this regard, the CMP process for planarization and an apparatus therefor, according to a conventional technique, are described below, with reference to FIGS. 1A and 1B.
During the CMP process, a wafer 11, 26 is polished by a pad 12, 24 and slurry 13, 28. A polishing table having the pad 12, 24 attached thereto simply moves around, and a head part 25 functions to exhibit pressing 21 at a predetermined pressure at the same time that rotation 23 and shaking 22 are performed. The wafer 11, 26 is mounted to the head part 25 under surface tension or in a vacuum. Due to the self load of the head part 25 and pressing 21 by the head part, the surface of the wafer 11, 26 is brought into contact with the pad 12, 24, and the slurry 13, which is a process liquid, is supplied into fine gaps 15 (pores of the pad) between the contact surfaces, so that a mechanical removal function is realized by the polishing particles in the slurry 13 and the surface protrusions 14 of the pad 12, and a chemical removal function is realized by the chemical component in the slurry 13.
In the CMP process, due to a pressing force applied between the wafer 11, 26 and the pad 12, 24, the device starts to come into contact with the pad at the upper portions of protrusions thereof. Such portions to which pressure is exclusively applied may have a relatively high surface removal rate. Accordingly, when the process progresses, these protrusions are reduced and uniformly removed over the entire area thereof.
Although the CMP may manifest advantageous properties with respect to a material removal rate (MRR), thickness uniformity, and surface quality, it has limitations in that it is an expensive process and is unsuitable for application to large areas.